The transition from a winterized, dormant sprinkler system to a fully operational one for the spring season requires careful, measured steps to prevent damage to the system’s plumbing and components. This process, often called “sprinkler system activation,” involves slowly reintroducing water pressure to the empty pipes and verifying that all parts are functional after cold-induced stress. Residential systems, which were likely drained or “blown out” with compressed air to prevent freezing, must be brought online with patience. Rushing the water flow can cause significant issues, making a systematic approach the most reliable path to activation.
Preparation and Main Water Access
Activating the system begins with a thorough visual inspection of all accessible components before any water is introduced. Locate the primary system elements, including the main water shutoff valve, the backflow prevention device, and the irrigation controller. Inspect all exposed sprinkler heads, risers, and valve boxes for signs of damage, such as cracked plastic, broken heads, or evidence of leaks from winter freezing and thawing cycles.
You must ensure that all winterization drain valves or bleeder valves are secured in the fully closed position before proceeding. These small valves, often found at low points in the system to facilitate drainage, must be sealed to hold pressure once the main water supply is opened. Verify the irrigation controller is set to the “off” or “standby” position to prevent any zones from activating prematurely, which could cause immediate flooding or further damage.
Pressurizing the System and Backflow Activation
The most critical step in the activation sequence is the slow, controlled reintroduction of water to prevent a phenomenon known as water hammer. Water hammer is a destructive pressure surge that occurs when a high-velocity column of water abruptly stops or changes direction, which happens if the main shutoff valve is opened too quickly into empty pipes. This sudden stop creates a shockwave that can easily crack pipes, damage fittings, and destroy valves, leading to costly repairs.
To avoid this, locate the main irrigation shutoff valve, typically a ball valve in the basement or near the water meter, and turn it very slowly, opening it only about a quarter of the way. Listen carefully as the water begins to trickle into the system, allowing the air trapped inside the empty main lines to slowly escape through the backflow preventer or even the furthest sprinkler heads. After a few minutes, once the sound of rushing water subsides, increase the valve opening to the halfway point, waiting again for the pressure to equalize before finally opening the valve completely.
After the main line is pressurized, the backflow prevention device, such as a Pressure Vacuum Breaker (PVB) or Reduced Pressure Zone (RPZ) assembly, needs activation. These devices prevent contaminated water from the irrigation system from siphoning back into the potable water supply. Ensure the test cocks are closed, then slowly open the first ball valve (closest to the water source) to pressurize the device itself. Next, slowly open the second ball valve (closest to the sprinkler system) to allow water to flow into the rest of the underground lateral lines.
Testing Zones and Adjusting Components
With the main lines pressurized, the next step is to manually activate each irrigation zone one at a time using the controller’s manual or test function. As a zone activates, observe the sprinkler heads; they will initially hiss and sputter as trapped air is expelled before a steady stream of water emerges. This manual run allows for immediate identification of major leaks, such as geysers from cracked pipes or excessive bubbling around fittings.
Inspect each operating sprinkler head for proper pop-up and rotation, looking for poor coverage, misting, or water spraying onto hardscapes like sidewalks or driveways. For spray heads, adjust the spray radius by turning the small screw located on top of the nozzle clockwise to reduce the distance. Rotor heads often require a flathead screwdriver or a specialized key to adjust both the arc (the rotation range) and the distance (radius). Fine-tuning the arc ensures the water pattern covers the intended area, ideally reaching “head-to-head” coverage where the spray from one head reaches the base of the next.
Setting the Controller for Seasonal Use
The final stage of activation involves programming the irrigation controller with a preliminary watering schedule appropriate for spring conditions. Begin by confirming the current time and date are correctly set on the unit. Most modern controllers require setting a start time, a run time for each individual zone, and specific watering days.
In the spring, water requirements are lower than in the peak summer months, so an initial, lighter schedule is often recommended. If summer requires a certain amount of watering per week, spring might only need half, which can be accomplished by reducing the run time or the number of watering days. Many controllers feature a “Seasonal Adjust” or “Water Budget” function, which allows you to globally adjust all zone run times by a percentage without reprogramming each zone individually. This initial schedule should be light to prevent overwatering and conserve resources while you monitor the system’s performance and confirm it is completely leak-free.